diff --git a/CHANGES b/CHANGES
index ee9b8d8dc..0b31563a7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -17,6 +17,8 @@ Python 2.7 support dropped.
 - :issue:`312`: ci: Add tmux 3.2a to CI
 - chore: Update black to `21.6b0
   <https://github.com/psf/black/blob/21.6b0/CHANGES.md#216b0>`_
+- :issue:`271`: Fix select_window() by providing the session ID as
+  argument to -t.
 
 libtmux 0.8.5 (2020-10-25)
 --------------------------
diff --git a/libtmux/session.py b/libtmux/session.py
index 5c3997266..0b19268bc 100644
--- a/libtmux/session.py
+++ b/libtmux/session.py
@@ -353,7 +353,10 @@ def select_window(self, target_window):
             assure ``-l``, ``-n``, ``-p`` work.
         """
 
-        target = '-t%s' % target_window
+        # Note that we also provide the session ID here, since cmd()
+        # will not automatically add it as there is already a '-t'
+        # argument provided.
+        target = '-t%s:%s' % (self._session_id, target_window)
 
         proc = self.cmd('select-window', target)